It is often necessary for an auto glass technician to remove a vehicle windshield from its frame in order to replace or repair the windshield. Typically, vehicle windshields are installed in a frame by bonding the windshield to the frame with a polymer adhesive such as polyurethane. Therefore, whenever it becomes necessary to remove a windshield, it is necessary to cut through the adhesive seal in order to release the windshield.
Many types of sealant cutting tools are known in the auto glass industry which are more or less specifically configured to cut the seal around a vehicle windshield. One type of manual knife used for this purpose has a generally cylindrical handle with an essentially planar, pointed blade which is bent some distance from the handle at an approximately 90° angle relative to the axis of the handle. Thus, the point of the blade is disposed roughly perpendicular to the centerline of the handle. This type of knife is often named a “cold knife” to distinguish it from other tools used in the auto glass industry which are powered or use heat to aid with the process of breaking the seal between the frame and the windshield.
A great deal of force is necessary to pull a manual sealant cutting tool such as a cold knife through the adhesive seal between a windshield and frame. Accordingly, typical sealant cutting tools often have a second handle pivotally connected to the primary handle near the blade attachment point. The second handle is often “T” shaped, and allows the auto glass technician to use both hands in pulling the blade through the strong adhesive.
During the use of a manual sealant cutting tool as described above, blades often become dull, bent, or broken. In addition, it can be quite difficult or impossible to adjust the length of the portion of the blade extending from the handle to effectively cut through the entire adhesive seal surrounding a windshield while simultaneously avoiding scratching or otherwise marring the exterior finish of a vehicle or to quickly exchange blades of various lengths.
Industry standard blades for a sealant cutting tool as described above typically have an elongated, planar attachment base perforated with mounting holes. Many sealant cutting tools are designed such that multiple steps and separate tools are necessary to attach or remove the mechanism used to secure the blade to the handle of the knife. Since the blades often break or become dull, a great deal of auto glass technician time is spent disassembling a typical sealant cutting tool to remove replace blades. In addition, many sealant cutting tools use the blade mounting holes to attach the blade to the handle of the tool. Thus, the blades can only be attached at fixed positions or fixed extensions with respect to the handle of the knife.
Cothery, U.S. Pat. No. 5,784,788, and Zuro, U.S. Pat. No. 6,256,889, both describe sealant cutting tools for use in the auto glass industry which feature mechanisms which are designed to allow the quick release and replacement of a blade from the tool handle. However, both Cothery and Zuro feature many intricate, movable parts which must be precisely machined, increasing the cost of a sealant cutting tool with a quick release blade feature, and potentially increasing the amount of maintenance necessary to properly use the tool. In addition, the prior art quick release tools feature separate blade carriages which move with respect to the handle which may introduce unwanted flexure into the cutting process. Also, the prior art is specifically configured to be used with industry standard cold knife blades. Thus, the utility of the prior art cutting tools for use with a variety of other blades including utility knife blades or pinchweld scrapers, for example, is limited.
The present invention is directed toward overcoming one or more of the problems discussed above.